OMP

Hi there.

So my MC-1 auto 200 from '89 is working just fine. I have stage 1 ECU and spring from QLCC ( 1.9 bar max).

However, I still have that very slight roughness while going over 3800-4000 rpm. It is more like a vibration. The car is very driveable but feeling that slight vibration.

This happens ( or at least noticeable) when the engine goes over upper part of the 3000 rpms.....Doing 80 mph the car will go just fine but if I do accelerate, the car will, and pretty well, but not as fast as I think it should......It is feeling like it is working harder and it doesn´t turn "happy"


I have posted this in some occasions in the past, and had some feedback from you guys about the knock sensor......But I have also had some feedback regarding the cranck position sensor and/or speed sensor.

First of all, no error codes at all and the car starts fine, does run pretty well in those sub-3000 rpms range. No vibrations, very solid drive. I am using 95 oct gas ( I leave in Spain and it is lowest oct gas available ( there is also 98)). Anyhow, spark plugs, wires, distributor, fuel pump, pressure accumulator, temperature regulator, etc, no vaccum leaks, Waste gate OK ( diaphragm).....Really, EVERYTHING. Engine was rebuilt completely 3 years ago ( and about 5000 milles from them)


So, at this point, the Knock sensor was changed some time back ( before the rebuilt). I think orginial ones were brown plug, but I think it wasn´t available and installed a green-connector one. So first of all. I think this is OK. Is that right? I know there were some issues of using the brown connector one versus the green connector one, but they are exactly the same. I just take this as OK. Am I right?

Then, reading about the cranck position sensor and the speed sensor.......Can these be just faulty? I always thought that these sensors were just GOOD or BAD, meaning that if they are not working, the car will just no start. It seems also that there are 2 different part numbers ( one for cranck position sensor and one for speed sensor), but again, it seems that they are interchangeable and thus, they can be interchanged between.

I remember that one of them was changed some years ago ( don´t remember which one of the 2).

So here are my questions : Can these go just "a little" bad?
Are thay really interchangeable?
These are the part numbers I found arounf the forum:

crank speed sensor: "034 905 381 A" grey in color
crank position sensor: "034 905 381" black in color

So they are not really the same.......

I am a little puzzle on this........Could these sensors be causing something like the behavior I am talking about? Or these do nothing but send signals for driveability ( and not "fine" driveability)....Could any performance issues be realted to these?

Thanks a lot
Cheers

Kneale Brownson

Never heard of either of those sensors causing performance issues. I thought both are used by the ecu to determine that conditions are proper to permit spark for starting. The only issues I've encountered with them is failure to let the engine start when they are beginning to go bad. The knock sensor can influence performance, I believe.

OMP

Thanks Kneale.

About the knock sensor, I am pretty sure it is not torqued at the right specs. Now, I am sending the car in a couple of weeks for some routine maintenance, and just wanted to double check this issue.

So, what would be the symptons of a knock sensor not tighten at the right specs ( 20 Nm in this case, right?).

If the timing is retarded, would this be much noticeable?

If the timing is retarded, for what I have read, I shouldn´t see high boost figures....Or is this something that has nothing to do with the timing being retarded?

I am asking because I have the impression that the car goes because I have the 1.9 Bar chip and spring and I am juts "pushing" all this air into the engine, but like posted on first post, the engine doesn´t "seem" to like it that much, even if it does go up to 1.9 with no big issues.

So, are the symptons of a tighten out of specs knock sensor ( or even, plain bad sensor ) would be something noticeable for the driver?
How does a car feel when the timing is retarded?

I have read a lot on this at it seems that the car clearly bucks/chokes on bad knock sensor, and mine doesn´t ( at all on any circumstance).
The car just feels "lazy" from 4000 rpm and it doesn´t pretty much to turn up there on the plus-3500 rpms on.


Thanks
Cheers